Well-bore sampling device and process for its use



May 2, 1968 H. K. VAN PooLLl-:N 3,384,170

WELL-BORE SAMPLING DEVICE AND PROCESS FOR ITS USE Filed Aug. 5, 1966/NVENTOR HENDRIK .,K. VAN POOLLEN United States Patent O 3,384,170WELL-BRE SAMPLING DEVICE AND PROCESS FR ITS USE Hendrik K. van Poollen,Littleton, Colo., assignor to Marathon Oil Company, Findlay, Ghio, acorporation of Ohio Filed Aug. 3, 1966, Ser. No. 575,914 9 Ciaims. (Cl.16S- 3) The present invention relates to new devices and pr-ocesses forthe sampling of uids within subterranean formations, and in particularrelates to the sampling of such uids from a plurality of elevationswithin well-bores.

In geological exploration, particularly in the logging of wells drilledfor the discovery and recovery of petroleum from underground formations,it is often desirable to sarnple an observation well at severalelevations within a reservoir. In most cases such sampling is preferablydone simultaneously at a number of different levels, and is generallyaccomplished by first perforating the casing of the well-bore, e.g. withgun or other conventional perforating means. Such sampling providesclear indication of the fluids available at different elevations withinthe borehole.

Some sampling tools allow sampling at one perforation while the otherperforations are in communication with each other. Such tools includethe Schlumberger wire line formation tester and various types ofstraddle-packer arrangements. This communication between perforations atvarious levels causes a co-mingling of the fluids within the well-bore.In some circumstances, fiuids from one perforation will fiow into thewell-bore and will ow outward through another perforation perhaps atlower elevation. Such cross flow requires large amounts of fluid to bewithdrawn from any one perforation if a representative sample is to beobtained. Withdrawals of such large amounts of fluid is difficult in therelatively limited size of sampling device which can normally beconveniently dropped down hole on a wire line. In addition, with largeamounts of uid being withdrawn from a single perforation, spherical flowwill take place in the reservoir and this will distort the fluid-fluidinterfaces in immediate vicinity of the wellbore. Particularly largewithdrawals will cause the observation well to become a sink and againthe fluid fronts will be distorted.

This problem of co-mingling of uids within the formation and its effecton the obtaining of a representative sample has been recognized andprevious attempts have been made to overcome this difficulty. Forexample, in U.S. Patent 2,781,663 filed Jan. 16, 1956, and issued Feb.19, 1957, it is mentioned that superimposed pressure may be applied tothe casing to prevent well fluids from entering the same while the toolis being placed in position. The difficulty with such techniques is thata gas is not suitable for this pressurization since it will merely raisethe total pressure within the Well casing and in many cases will notprevent cross flow between the perforations in the casing. 'If a liquidis used, there is the difficulty of an additional pumping of thewell-bore and the additional complication of contamination of thesamples by the pressurizing liquid.

Also, any fluid which is used to pressurize the well-bore will, ofnecessity, have a greater pressure than that of the fluids in theformation and therefore will ow into the formation at least to somedegree. This flow of a nonrepresentative pressurizing fluid into theformation can distort the equilibrium within the formation and causesamples which are later taken, t-o be non-representative.

All such detrimental effects can be avoided by the use of the samplingdevices of the present invention. Through their use only substantiallyhorizontal ow will take place and samples may be drawn simultaneously ata number of 3,384,l70 Patented May 2l, 1968 ice perforations. By keepingthe well-bore closed off at other times, only very small amounts offluid will have to be Withdrawn from the formation in order to obtainrepresentative formation fluid samples.

The sampling devices of the present invention comprise sampling chamberspreferably disposed vertically one over the other, each such chamberhaving at least one aperture equipped for sealing in communication witha perforation in the well casing. Valves, or other means for closing theapertures, are preferably provided. In addition, the present inventioncomprises sealing means for sealing the perforations in the well casingat those times when the sampling device is not in position forwithdrawing samples. These sealing means can be any of a variety ofdevices, including among the particularly preferred embodiments, acylindrical sleeve which seals the perforations and into which thesampling device can be slid, the sleeve having openings which can bebrought into alignment with the perforations in the well casing whensampling is to be accomplished, or can be moved away from theperforations in the well casing when the sampling device is withdrawnfrom the sleeve.

In another preferred embodiment the sealing means is a dummy samplingdevice which is suspended below the actual sampling device by adetachable Wire line or electrically operated hook. When the samplingcontainer is lowered into the well it displaces the dummy downward sothat the lsampling device can communicate with the perforations of thewell-bore. When the sampling device is withdrawn the dummy is pulledupward until it seals off the perforations in the well-bore and thedummy is then disconnected so that the sampling device can be withdrawnfrom the well-bore. The invention will be more fully understood byreference to the descriptions of the specic embodiments which follow.

FIGURE l is a schematic diagram of the device of the present inventionin which the perforations are sealed by a hollow sleeve.

FIGURE 2 shows the sealing device of FIGURE 1 deflected to the samplingposition and containing a sampling device.

FIGURE 3 shows a second embodiment of the invention in which a dummysampling device is used to seal off the perforations in the well-borecasing at times when the actual sampling device is not in position forsampling. FIGURE 3 shows the sampling device in sampling position withthe dummy hanging underneath.

FIGURE 4 shows the embodiment of FIGURE 3 with the sampling device inthe process of being raised to the surface and the dummy in position toseal the perforations in the casing.

In FIGURE 1 the well casing 1 has been cemented in place in thewell-bore and contains perforations produced by conventional perforationtechniques in such manner that no significant burrs are present on theinside of the casing. This may be accomplished by the use of perme'atersor abrasive jet perforation or bullets or one of the various shapedcharges which are commercially availtable and which leave essentially noburr. The casing has been equipped with a no-go shoulder 3 to facilitatealignment of the sampling devices with the perforations. Any of a numberof stops can be used in place of the no-go shoulder. For example,inflatable packers, removable expansion rings or even a stud welded tothe inside wall of the casing, may be utilized or careful calibration ofthe wire line can be used to position the sampling devices. A series -ofapertures 5 extend through the wall of the casing and are so spaced asto be capable of coinciding with the perforations 2 in the casing.However, in FIG- URE 1 the sleeve 4 is displaced so that the apertures 5do not communicate with the perforations 2. A series of seals 6 seal theapertures 5 against the casing 1 and are capable of sealing theapertures in communication with the perforations 2, when the sleeve 4 issuitably aligned. The O-rings 6 extend circumferentially around thesleeve 4 forming a girth seal and these O-rings are held in place bybands V13 which extend around the sleeve 4 and partially confine theO-rings. The sleeve assembly can be forced down the well-bore asnecessary by having, for example, a 200 pound or larger sinker bar.Various other refinements, including retraction mechanism for retractingthe seals until the sleeve is in place, may be employed. Well pipe of alarger diameter may be used from the formation to the surface 4andcentralizers may be added to the sleeve in order to keep the seals fromrubbing against the hydraulic plate, as the sleeve is lowered down theWell-bore. In FIGURE 1 no substantial flow into the well-bore occursfrom the perforations 2 and virtually no cross flow between theperforations is possible.

FIGURE 2 shows the sleeve 4 of FIGURE l with the sampler 7 in place inthe sampling position. The sampler consists of a number of fluidchambers 12 each having an aperture 14 equipped with a check valve -1'1to prevent flow outward from the chambers. The apertures 14 on thesample chamber are isolated by a series of O-rings 15 and retainingrings 16 similar to those used on sleeve 4. When the sampling device 7is lowered into the sleeve 4 the bottom of the sample device strikes ano-go shoulder yt5 in the sleeve. This displaces the sleeve downwarduntil it strikes the no-go shoulder 3 inserted in the well-bore. Asmentioned above, this no-go shoulder `3 may be replaced by a stud,packer, slack wire line or other means for stopping the downward travelof sleeve 4 when the apertures 5 are in alignment with the perforations2 in the well casing. Similarly, other alignment devices may be used inplace of the no-go shoulder 8 to align the `apertures 14 in the samplingdevice 7 with the apertures -'5 in the sleeve.

The sample containers may be conventionally evacuated or vented toperimt fluids to flow freely into them. Because the casing perforations2, the sleeve apertures 5, yand the sampling container apertures 14 areall in alignment, fluids flow from points in the formation into samplingchambers at approximately the same elevation as the p'oints from whichthe fluids leave the formation.

The embodiment shown in FIGURE 2 and the other embodiments of theinvention are adaptable to a wide variety of conventional modificationsand auxiliaries including, for example, a pass-through tube which canrun the full length of the sampling device 7 passing through each of thechambers 12 without communicating with them so that the fluids canfreely flow from the top to the bottom or from the bottom to the top ofthe sampling device as it is being raised or lowered in the well-borerespectively. This prevents a piston action and facilitates withdrawaland insertion of the sampling device. Electric or hydraulically operatedvalves may be included on either the sleeve 4 or the sampling device 7.Also, electric or hydraulic actuators may be used instead of wire linesto provide the necessary displacement of the sleeve and of the samplingcontainer within the wellbore. For example, an inflatable packer may beincorporated at the bottom of the sleeve 4 so that the packer may beinflated to substitute for the no-go stop 3. As a further variation, anelectric actuator attached to such a packer can be used to raise andlower the sleeve 4 while `the packer remains in a fixed position in thewell-bore, thus cutting off or permitting flow through the sleeveaperture-s 5 according to the position of the sleeve. Further, it is notnecessary that either the sleeve or the sample container be deflectedvertically to commence or discontinue flow through their respectiveapertures. Instead, `other sealing means may be provided for controllingsuch flow without deflection of the unit itself, or the sleeve orsampling device may be rotated into or out of alignment with theapertures in the surrounding element.

tIn the latter instance, suitable longitudinal seals can be provided tocut off flow when the apertures are not in alignment.

FIGURE 3 shows a second preferred embodiment of the devices of theinvention which utilizes a dummy sampling device to plug the apertures 2in the well casing When the sampling device .20 is not in the samplingposition as it is shown in FIGURE 3. The sampling device 20 may besimilar to the sampling device 7 shown in FIGURE 2 except that thesampling device in FIGURE 4 is of sufciently large diameter as to be atight t in the well casing. O-rings 211 confined in retaining rings 22`and so positioned as to isolate apertures 24 which lead into theindividual compartments 26 of the sampling container, and check valves23 located in such said apertures are all provided as previouslydescribed under FIG- URE 2. A dummy 27 provided with O-rings 29 andsubstantially the same spaced relationship as the O-rings on thesampling device 2G hangs below the sampling device by means ofdetachable hooking device 2S. This hooking -device may be electrically,mechanically, or hydraulically actuated in response to signals from thesurface, or in response to the striking of an alignment pin which can beset into the well casing. A no-go stop 32 or its equivalent, isinstalled into the well casing in such position that when the dummybottoms on no-go stop, the sample device is in position so that itsapertures can withdraw samples from the well casing perforations 2.By-pass tubes 30 and 31 are provided in the sampling device and dummy,respectively in order to prevent a piston action as they move up anddown the well-bore.

FIGURE 4 shows the dummy 27 in position for blocking flow from the wellcasing perforations 2.

In actual practice the dummy will first be placed in the position shownin FIGURE 4 and the well then pumped dry of fluids and the formationpermitted to reach equilibrium. Then the sampling device Ztl will belowered down into the well-bore until it strikes the dummy 27 anddeflects the dummy until it bottoms on the no-go stop 32 as shown inFIGURE 3. Sample will then be taken, either immediately or by theactuation of any electric valves or other aperture closing devices whichmay be additionally located on the apertures of the sample container 24as described above under modifications which are possible with theembodiment of FIGURES 1 and 2. After the sampling chambers 26 havereceived the samples the sampling device 20 is raised until thedetachable hook or other coupling 28 have pulled the dummy 27 into theposition shown in FIGURE 4. The hook 28 is then detached and thesampling device 20 raised to the surface.

While the above described embodiments have been discussed as being usedfor the obtaining of samples which are then raised to the surface, itshould be understood that the usual conventional techniques oftelemetry, i.e. the remote measurement of rate of fluid flow, pressure,temperature, etc. may all be employed 'with the devices of the presentinvention without removal of the sampling device from the well-bore. Thesampling chambers may readily be equipped with one or more pumps inorder to permit them to be emptied after measurement of the desiredphysical properties and telemetering of the data to the surface. Thesampling chambers may then be reused to once again sample fluids fromthe` formation without bringing the sampling device to the surface.

A variety of other modifications and Variations will be apparent tothose skilled in the art upon a reading of the present specification andit is to be understood that the above embodiments are merelyillustrative of the invention and that the claims appended hereto are tobe taken as including all such apparent modifications and variations ofthe invention.

What is claimed is:

1. A fluid sampling device for simultaneously sampling fluids from aplurality of levels within a well-bore having a perforated well casingwhich preventing substantial mixing of fluids from different elevationsin the well-bore and additionally preventing such mixing within thesample device, said device comprising in combination: a sampling devicehaving a plurality of fluid-tight compartments for retaining fluidsamples, each said compartment having at least one closeable aperture,said apertures being so positioned as to correspond with perforations inthe well casing and being fitted with sealing means for sealing saidapertures in communication with the perforations in the well casing;means for sealing the perforations in the well casing to preventsubstantial flow through said perforations into said well-bere at timeswhen said sampling device is not positioned for sampling said fluids;means for displacing said perforation sealing means at times when saidsampling device is positioned for sampling.

2. The device of claim 1 wherein the apertures and said sealing meansare positioned by lowering them until they contact a no-go stoppingmeans.

3. The device of claim 1 wherein the perforation sealing means comprisesan outer sleeve having perforations coinciding with the elevations ofsaid casing perforations through which fluid is to be sampled, saidapertures having sealing means external to said sleeve, said sealingmeans being designed for sealing said perforations in communication withsaid apertures, said outer sleeve being displaceable so that saidperforations can be sealed by displacing said sleeve so that saidperfor-ations are not in communication with said apertures in saidsleeve, means for displacing said sleeve so that said aperturesalternately communicate with said perforations and do not communicatewith said perforations.

4. The device of claim 3 wherein the displacement of said sleeve isaccomplished by raising or lowering said sleeve by means of a wirelinecontrolled from the surface.

5. The device of claim 1 wherein the perforation sealing means comprisesa substantially cylindrical dummy sampling device which seals saidperforations but does not communicate with said perforations, said dummysampling device being capable of vertical displacement so as to unsealsaid perforations when the sampling device of claim 1 is positioned forsampling.

6. The device of claim 5 'wherein the displacement of said sleeve isaccomplished by raising or lowering said sleeve by means of a wire linecontrolled from the surface.

7. A fluid sampling device for simultaneously sampling fluids from aplurality of levels within well-hole while preventing substantial mixingof fluids from different elevations in the borehole and additionallypreventing such mixing within the sampling device, said devicecomprising in combination: an outer sleeve having apertures coincidingwith the elevations from which fluid is to be sampled, said apertureshaving sealing devices external to said sleeve, said sealing devicesbeing designed for contacting perforations in the outer walls of saidwell-bore; a substantially cylindrical sampling device having aplurality of fluid-tight compartments for retaining fluid samples, eachsaid compartment having at least one close-able aperture, said aperturesbeing so positioned as to correspond with the apertures in said sleeveand being fitted with sealing means for sealing said apertures incommunication with the apertures in said sleeve, said sample containerbeing sufficiently small in diameter as to permit its insertion withinsaid sleeve; means for raising and lowering said sleeve and said samplecontainer into and out of a wellbore; means for cutting olfcommunication between said -apertures in said sleeve and said aperturesin said sample chamber, whereby when said sleeve is positioned withinsaid well-bore so that the apertures in said sleeve coincide with theapertures in said well-bore, said sample container may be insertedwithin said sleeve and positioned so that the apertures of said samplecontainer communicate through the apertures of said sleeve with theapertures of said well-bore and so that each of said apertures iscircumferentially sealed to prevent cross flow and mixing of fluids fromdifferent elevations within the well-bore.

8. A process for simultaneously sampling fluids from a plurality oflevels within a well-bore while preventing substantial mixing of fluidsfrom different elevations in said wellbore and additionally permittingsuch mixing within the sampling device, said process comprising, incombination, the steps of perforating said well-bore casing at aplurality of elevations, sealing said perforations with perforationsealing means, allowing sufficient time to elapse to permit the fluidswithin said formation to come to substantial equilibrium, positioningsaid sampling device for said sampling of said fluids, after orimmediately before said positioning of said sampling device, deflectingsaid perforation sealing means so as to unseal said perforations,thereafter withdrawing samples through said perforations into saidsampling device while preventing mix ing of said samples within thebore-hole and within the sampling device.

9. The process of claim 8 wherein the sealing and unsealing of saidperforations is accomplished by raising and lowering a wire linecontrolled at the surface.

References Cited UNITED STATES PATENTS 2,452,466 10/ 1948 Iaswell166-179 2,564,198 8/1951 Elkins 166-3 2,781,663 2/1957 Maly et al 166-33,067,819 12/1962 Gore 166-179 JAMES A. LEPPINK, Primary Examiner.

1. A FLUID SAMPLING FOR DEVICE FOR SIMULTANEOUSLY SAMPLING FLUIDS FROM APLURALITY OF LEVELS WITHIN A WELL-BORE HAVING A PERFORATED WELL CASINGWHICH PREVENTING SUBSTANTIAL MIXING OF FLUIDS DIFFERENT ELEVATIONS INTHE WELL-BORE AND ADDITIONALLY PREVENTING SUCH MIXING WITHIN THE SAMPLEDEVICE, SAID DEVICE COMPRISING IN COMBINATION: A SAMPLING DEVICE HAVINGA PLURALITY OF FLUID-TIGHT COMPONENTS FOR RETAINING FLUID SAMPLES, EACHSAID COMPARTMENTS LEAST ONE CLOSEABLE APERTURE, SAID APERTURES BEING SOPOSITIONED AS TO CORRESPOND WITH PERFORATIONS IN THE WELL CASING ANDBEING FITTED WITH SEALING MEANS FOR SEALING SAID APERTURES INCOMMUNICATION WITH THE PERFORATIONS IN THE WELL CASING; MEANS FORSEALING THE PERFORATIONS IN THE WELL CASING TO PREVENT SUBSTANTIAL FLOWTHROUGH SAID PERFORATIONS INTO THE WELL-BORE AT TIMES WHEN SAID SAMPLINGDEVICE IS NOT POSITIONED FOR SAMPLING SAID FLUIDS; MEANS FOR DISPLACINGSAID PERFORATION SEALING MEANS AT TIMES WHEN SAID SAMPLING DEVICE ISPOSITIONED FOR SAMPLING.
 8. A PROCESS FOR SIMULTANEOUSLY SAMPLING FLUIDSFROM A PLURALITY OF LEVELS WITHIN A WELL-BORE WHILE PREVENTINGSUBSTANTIAL MIXING OF FLUIDS FROM DIFFERENT ELVEATIONS IN SAID WELL-BOREAND ADDITIONALLY PERMITTING SUCH MIXING WITHIN THE SAMPLING DEVICE, SAIDPROCESS COMPRISING, IN COMBINATION, THE STEPS OF PERFORATING SAIDWELL-BORE CASING AT A PLURALITY OF ELEVATIONS, SEALING SAID PERFORATIONSWITH PERFORATION SEALING MEANS, ALLOWING SUFFICIENT TIME TO ELAPSE TOPERMIT THE FLUIDS WITHIN SAID FORMATION TO COME TO SUBSTANTIALEQUILIBRIUM POSITIONING SAID SAMPLING DEVICE FOR SAID SAMPLING OF SAIDFLUIDS, AFTER OR IMMEDIATELY BEFORE SAID POSITIONING OF SAID SAMPLINGDEVICE, DEFLECTING SAID PERFORATION SEALING MEANS SO AS TO UNSEAL SAIDPERFORATIONS, THEREAFTER WITHDRAWING SAMPLES THROUGH SAID PERFORATIONSINTO SAID SAMPLING DEVICE WHILE PREVENTING MIXING OF SAID SAMPLES WITHINTHE BORE-HOLE AND WITHIN THE SAMPLING DEVICE.